Adeno-associated Virus Biology And Utilization For Gene Transfer

National Institute Of Dental & Craniofacial Research

Investigators

Linked publications, trials & patents

Abstract

Much of our research efforts are centered on the hypothesis that by understanding the changes in gene expression we can identify the drivers of the dysfunction that underly the causes of many diseases and through gene therapy alter this flow of information to restore function. Since the initiation of our program in 2000 we have worked to develop adeno-associated virus (AAV) vectors that can be used to alter this flow of information both as a tool in functional genomics but also as a therapeutic intervention. We have developed many vectors that are currently used in many diverse applications, our focus has been on applications in the salivary glands and oral cavity. The first project area aims to characterize the interactions that define viral tropism, (i.e. the interactions that define cell-type specificity) and define the different functional domains on the viral particles. Our hypothesis has been that by understanding the structure of the viral particle we can make targeted functional changes and develop a better vehicle for gene transfer and increasing its utility. As our understanding of the interactions necessary for AAV transduction has advanced, we have mapped these sites on the surface of the particle. Our previous work using crystallography identified the sialic acid binding site on AAV5, which we have modulated to recognize distinct forms of sialic acid and alter tropism. Our recent work on mapping interactive antibodies on the surface of AAV5 also highlighted the same region. Targeted mutagenesis of this region could further reduce the immunogenicity of AAV5 without altering transduction. The second area focuses on the development and application of new AAV vectors, with particular interest in vectors that target cell types directly related to the mission of the NIDCR. We have demonstrated that AAV44.9, a non-heparin, non-sialic acid-binding AAV has broad tropism and is able to transduce the acinar cells of the parotid gland, photoreceptors in the eye, and cardiac tissue. Characterization of the glycan binding activity identified that cell surface glucose and glucosamine are responsible for its tropism. In several publications, we describe the use of AAV vectors for the treatment of different diseases, including hereditary hearing loss, cystic fibrosis, and diabetes. Our main focus for application of AAV vector technology is the salivary gland. In 2016, a phase 1 clinical trial was initiated to evaluate the safety and efficacy of AAV2 driven AQP1 expression in the parotid gland of individuals with radiation-induced salivary hypofunction. In response to the pandemic, we shifted our efforts and resources to developing AAV vectors as both a traditional vaccine platform for expressing antigen and to express neutralizing antibodies that could be used in passive genetic immunization against COVID19. This work was recognized with the award of a Intramural Targeted Anti-COVID 19 (ITAC) grant. Members of our team also contributed to research that identified the oral cavity as a site of SARS-CoV2 infection, the impact of masks, antibody-based diagnostics, immune dysfunction, vaccine efficacy and mechanisms of SARS-CoV2 pathogenesis. The third project area focuses on understanding the etiology of Sjgrens disease (SjD). By combining the gene transfer ability of AAV vectors with our data on key populations of Sjgrens, non-Sjogrens sicca patients, or healthy volunteers we have, i) identified epithelial gene changes related to the disease associated salivary hypofunction, ii) developed a novel therapy for Sjgrens, (Aquaporin gene therapy) which is moving towards initiation of a clinical trial, and iii) better targeted current therapies to subsets of SjD patients based on their transcriptome and autoantibody profile. In addition, we have worked to understand the effects of chronic viral infection on gland function. Our future research will build on our current work with the goals of improving the transduction activity of AAV vectors and developing a better understanding of parvovirus biology. Just as our work with AAV has led to a trial for the treatment of radiation-induced xerostomia, we anticipate our continued studies of the basic biology of AAV will also translate into better vectors for new therapies in diseases with unmet clinical need.